In general, electrical circuits of large-size electronic appliances, such as an LCD TV and a PDP TV, include a protective device such as a thermal fuse resistor at a power input terminal in order to prevent appliance breakdown caused by an inrush current, the increase of an internal temperature or a continuous over current occurring when the electronic appliance is powered on, so that a power circuit may be protected.
The thermal fuse resistor includes a resistor and a thermal fuse, and the resistor is connected to the thermal fuse in series through lead wires.
In addition, according to the thermal fuse resistor, the resistor and the thermal fuse are packaged in a case and fillers are filled in the case, so that electronic parts can be protected from being damaged by fragments produced when the fusible member is melted.
The fillers have the form of slurry including silicon dioxide (SiO2) to improve the heat-resistant, conductivity and a curing property. The case is made of ceramic used in the case of a typical resistor.
An end of the lead wire extends out of the case, and the thermal fuse resistor according to the related art is mounted on a printed circuit board (PCB) in such a manner that the resistor and the thermal fuse are erected on the PCB by soldering the end of the lead wire on the PCB.
Accordingly, when an inrush current is introduced, the thermal fuse resistor restricts the inrush current to predetermined current by using the resistor. When the over current is introduced, the thermal fuse resistor transfers heat emitted from the resistor to the thermal fuse through the filler to disconnect a circuit such that the fusible member provided in the thermal fuse and including solid-phase lead (Pb) or polymer pellet is melted, thereby protecting electrical circuits of the electronic appliances.